Abstract : In this article, we examine the case of international organizations promoting dams who adopted PSD norms under the influence of non-state and non-hegemonic actors, notably development, humanitarian, and environmental NGOs. This adoption has had a noticeable effect: whereas, during the 1980s, only about 20% of dam projects included participation in the decision-making process, 10 years later that number had risen to 50% . Two observations can be made. Firstly, there has been a dissemination of PSD norms and principles among different actors to varying degrees, the effect of which has been more than rhetorical, since the dam projects themselves have been affected. Secondly, these norms have been internalized to the extent that actors not only take them into account but also seek to transform them into internal or external practices. Our hypothesis is that these internalization efforts depend in large part on the degree to which the actors perceive the norms as legitimate. The process however varies according to both the nature of the norm in question and the degree to which it is internalized.